[mapserver-users] Dynamin SQL with mapserver CGI?
Fawcett, David
David.Fawcett at state.mn.us
Tue Jan 27 09:42:49 EST 2009
Right.
I believe that several layers to the onion are good.
In other words, I wouldn't have my Web application logging into my db as the admin user even if I was using validation on my input.
David.
-----Original Message-----
From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of umn-ms at hydrotec.de
Sent: Tuesday, January 27, 2009 2:14 AM
To: MapServer
Cc: Steve Lime; David Fawcett
Subject: RE: [mapserver-users] Dynamin SQL with mapserver CGI?
I think validation patterns are a real solution to the problem and minimizing access-priviliges is not.
When filter with URL-substitution is used without validation patterns, one relies on the security-system of postgres.
This is acceptable in most intranets but hazardous in the internet.
Look for example at http://www.postgresql.org/support/security.html what can be done with even a minimal-postgres-login
Ciao
Benedikt
Extract of the http://www.postgresql.org/support/security.html
* Three vulnearbilities in the regular expression handling libraries can be exploited to cause a backend crash, infinite loops or memory exhaustion. This vulnearbility can be exploited through frontend applications that allow unfiltered regular expressions to be passed in queries.
* A bug in the handling of SET ROLE allows escalation of privileges to any other database user, including superuser. A valid login is required to exploit this vulnerability
* Calling COALESCE() with two NULL parameters would cause the current backend to crash, causing a denial of service. A valid login is required to exploit this vulnerability.
* Public EXECUTE access is given to certain character conversion functions that are not designed to be safe against malicious arguments. This can cause at least a denial of service. A valid login is required to exploit this vulnerability
"Steve Lime" <Steve.Lime at dnr.state.mn.us> schrieb am 26.01.2009 21:29:52:
> In addition, one can and should apply validation patterns to variables
> used in SQL. That way MapServer
> can test the input data before handing off to PostGIS or whatever.
>
> These patterns are set in LAYER metadata. For example:
>
> LAYER
> ...
> DATA"'the_geom FROM (SELECT the_geom FROM my_table WHERE ID = '%id%')
> as foo USING UNIQUE OID"
> METADATA
> id_validation_pattern '^[0-9]{3}$'
> END
> END
>
> This tells the CGI to test the request parameter against the regex
> '^[1-9]{3}$'. The regex says that the value
> of the id variable must be an number exactly 3 digits long with no
> zeros. Any attempt to send a value other
> than that will generate an error message. The CGI code does not force
> the use of validation.
>
> Validation like this will be further expanded in 5.4 with the addition
> of a new validation object. So you'd see
> something like:
>
> LAYER
> ...
> VALIDATION
> 'id' '^[0-9]{3}$
> END
> END
>
> Steve
>
> >>> On 1/26/2009 at 8:47 AM, in message
> <6246727221874A4FB8D3F9BBC37D9BD5056DA174 at s-sp22.pca.state.mn.us>,
> "Fawcett,
> David" <David.Fawcett at state.mn.us> wrote:
> > Of course, part of security is also having your application hit your
> database
> > as a user that only has the rights that it needs. If your user only
> has
> > select rights on only the data that you want to expose, that should
> help
> > limit some of these issues.
> >
> > -----Original Message-----
> > From: mapserver-users-bounces at lists.osgeo.org
> > [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of
> > umn-ms at hydrotec.de
> > Sent: Monday, January 26, 2009 4:43 AM
> > To: MapServer
> > Subject: Re: [mapserver-users] Dynamin SQL with mapserver CGI?
> >
> >
> >
> > > Not any great hazard, I believe, ...
> >
> > Mmh. I'd be cautious.
> >
> > Example:
> > * Mapfile:
> > DATA "the_geom from buildings"
> >
> > * Set Filter via URL to this:
> > 1=1);DELETE FROM OTHERTABLE; DECLARE X BINARY CURSOR FOR
> SELECT * from
> > buildings WHERE (1=1
> >
> > I think Mapserver will create the following statements: (I've
> added
> > newlines)
> > DECLARE mycursor BINARY CURSOR FOR SELECT the_geom from
> buildings WHERE
> > (1=1);
> > DELETE FROM OTHERTABLE;
> > DECLARE X BINARY CURSOR FOR SELECT * from buildings WHERE (1=1)
> and (%s &&
> > setSRID( ...) )
> >
> > Mapserver calls PQExec with these statements. PQExec will
> execute every
> > statement and will return
> > the results of the last one.
> >
> > Bye
> > Benedikt Rothe
> >
> >
> > "Rahkonen Jukka" <Jukka.Rahkonen at mmmtike.fi> schrieb am
> 26.01.2009 09:34:31:
> >
> > > Hi,
> > >
> > > Not any great hazard, I believe, if it means that user can
> normally
> > > get all the features, but only a subset when filter is set.
> It is
> > > different case if DATA clause is manipulated, and therefore
> that
> > > must be connected to DATAPATTERN.
> > >
> > > -Jukka Rahkonen-
> > >
> > > Lähettäjä: mapserver-users-bounces at lists.osgeo.org [mailto:
> > > mapserver-users-bounces at lists.osgeo.org] Puolesta
> umn-ms at hydrotec.de
> > > Lähetetty: 26. tammikuuta 2009 10:03
> > > Vastaanottaja: MapServer
> > > Aihe: Re: [mapserver-users] Dynamin SQL with mapserver CGI?
> >
> > >
> > > Hi
> > >
> > > > You can use a replaceable parameter in the FILTER clause if
> all you ...
> > > This introduces the hazard of SQL-Injection, doesn't it?
> > >
> > > Bye
> > > Benedikt Rothe
> > >
> > > mapserver-users-bounces at lists.osgeo.org schrieb am 24.01.2009
> 14:04:42:
> > >
> > > > On Sat, Jan 24, 2009 at 3:18 AM, Saka Royban
> <srph124 at yahoo.com> wrote:
> > > > > Hi all
> > > > > I'm looking for a way to change SQL dynamically via URL
> parameters. it
> > > > > sounds from doc that changing DATA element in map file is
> impossible. Is
> > > > > there any other way?
> > > >
> > > > You can use a replaceable parameter in the FILTER clause if
> all you
> > > > want to do is alter the WHERE clause. So for example:
> > > > FILTER "%criteria%"
> > > > and
> > > > criteria=id='value'
> > > > would work with a database like Postgres.
> > > >
> > > > When working with a database you put the whole SQL WHERE
> clause in the
> > > > FILTER, whereas with shapefiles or ORG data sources you use
> the
> > > > FILTERITEM and FILTER.
> > > >
> > > > --
> > > > Richard Greenwood
> > > > richard.greenwood at gmail.com
> > > > www.greenwoodmap.com
> > > > _______________________________________________
> > > > mapserver-users mailing list
> > > > mapserver-users at lists.osgeo.org
> > > > http://lists.osgeo.org/mailman/listinfo/mapserver-users
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